New to off grid solar

off grid newby

New Member
Joined
Oct 6, 2021
Messages
4
Afternoon all. I am just getting into solar for off grid, but due to property location it is my only option.

I have enjoyed your videos and have been trying to digest as much info as possible from all sources to make the right decisions starting out. Initially will be only powering an RV sufficiently to run an AC as needed (currently using generator), but once the 1500 sq. ft. cabin is complete will need fully self sufficient system for HVAC, pump, appliances, etc.

I want to build a 48 volt system, and planning forward to expand taking into account current product availability, I feel like I need to purchase all inverters now to insure compatibility when placing in series later. I welcome any feedback on whether best to purchase (2) MPP LV6548 6.5KW or (3) Growatt SPF 5000 KW (for about the same price as (2) MPP)? Growatt is also available with MPP on backorder.

Thanks in advance for any input...
 

Rednecktek

Solar Addict
Joined
Sep 8, 2021
Messages
427
When you're planning your cabin layout, don't forget to pan where you're going to stick all the batteries and inverters and such, you don't want to have to mount them in the kitchen. :)

Also, south facing roof!

Go for the 2 MPP's. Getting 3x of the Growatts lets you do 3-phase, which almost nobody uses and you'd need 4 to double up the split-phase you'll want for your AC and pumps and such.
 

Porch

Solar Addict
Joined
Jan 17, 2021
Messages
267
Most people call 1,500 a small house. But to each it's own.
If you insulate and build the "cabin" with saving power in mind, you may not need so much of it. Split unit AC sip power, and LED lights are efficient.
 

Steve_S

Offgrid Cabineer, N.E. Ontario, Canada
Joined
Oct 29, 2019
Messages
5,404
Location
Rural NE Ontario Canada
I am 100% Offgrid, rural & remote and was NOT ever going to pay Big Power $55,000 to bring their poles up here, for the privilege of paying Monthly Indentured Servant Fees !

A Few things to understand which are ESSENTIAL !
The BIGGY: Energy Conservation is FAR Cheaper than Generation &/OR Storage !
- Build the most energy efficient structure you can.
- Make use of the Natural Features of the land you are on, look for Windbreaks, where the breezes blow, where the snow drifts in winter and where the water (melt) goes in spring
- Make use of Shade Trees to shade the Home (keeping it cooler) during the Hottest Periods.
- Use Evergreens to create Wind Breaks to protect from North Winds if applicable.
!! NOTE: Ground Mounted Solar Racking is more optimal than Roof Mounted systems due to the ability to set a Good "Year Round" angle setting OR then can be adjustable to optimize generation 4 times a year. Trackers are Extremely Expensive but that is an option.

--- PLAN your home for efficiency concerns !
IE: Use an On-Demand Water heater as opposed to a Tank ! Think of the "Tank" as the same as leaving your car idling in the driveway all day long just because you Might want to take a drive to the store... It IS Idiotic to heat water for 15 minutes of every hour "just because". Keep your Water Lines SHORT so locate Water Heater near points of use (between washroom & kitchen usually best) to minimize pipe run lengths and INSULATE the Pipes (Cold & Hot !)

Using a COOL-ROOF System creates a Thermal Break between the actual physical structure & roof "face". This prevents Heat Gain from being passed into the Home by using Natural Convection to vent the heat away from the home. In Winter this also prevents cold/snow from contacting the roof "face" which eliminates heat loss due to cold transfer because of the thermal break. SEE ATTACHED PDF'S. NOTE this is covered in Green Building Advisor, and many other sites... Several Nations have included such within their Building Codes as well.

Siding Systems can also cut Huge Energy Costs if correctly implemented when considered from the outset. A RainScreen Siding System acts similarly as a Cool Roof system, by creating a Passive Envelope around the structure resulting in a Thermal Break between the exterior environment and the structure shell.

An Optimal Configuration is to use the Combination of Cool Roof and Rainsreen Siding as a passive thermal management system. My Own Home uses BOTH of these plus more techniques for efficiency. Air is pulled behind the siding up through the soffit through the roof and out the Ridge Vents which creates a passive vaccum preventing any moisture or condensation and an active thermal break.

Examples:
Hot Summer Day (Heat Wave) 40C/104F outside. Inside my home (With NO AC only windows open) 28C/82F. Temp at Peak of Cathedral Ceiling 29C/84F
Cold Winter Day -30C/-22F outside. On-Demand (In-Floor concrete slab Radiant Heating) will run a MAX of 2 Hours within a 24 hour period to maintain a Floor/Slab temp of 25C/77F.
*NB: I have No Basement, I have an FPSF (Frost Protected Slab Foundation) with 4" Thick HD-XPS Foam under it and on it's sides... It has 7/8" Radiant Pex Heating embedded within the Thermal Mass Slab. Radiant System supplied by https://www.radiantcompany.com/ (EXCELLENT DIY SHOP)

Hyper-Efficient which also lists appliances etc used
NOTE: I designed, did the plans & blueprints and built the house myself, only contracting out the concrete forming & pour and the actual cladding of the roof in metal. Everything else, including milling my own Pine 6" patterned baseboards, casings and moldings all done by me.

My Cabin Overview:
  • 500 Sq Feet, 1 br, 2nd story loft, 9/12 pitch roof (Cathedral Ceilings)
  • FPSF Slab Foundation REF LINK: https://www.finehomebuilding.com/2010/11/11/frost-protected-shallow-foundations-2
  • Radiant Heating in floor (*it's WONDERFUL and efficient) provided by REF: https://www.radiantcompany.com/
  • Cool Roof System (saved 25-30% of Heating & Cooling costs and is incredible ! REF: http://www.houstoncoolmetalroofs.com/cool-roof-information/cool-roof-design-texas/
  • Rain Screen Siding method (used Live Edge White Cedar as my finish) REF: https://www.greenbuildingadvisor.com/article/all-about-rainscreens
  • INSULATION: (All obtained from Commercial Roofers - not available in retail land)
  • -- 4" XPS Under the FPSF Slab and out the sides (wings) 24" providing R20, double code requirement.
  • -- 5.25" High Density EPS-2 Foam between 2x6 studs R32)
  • -- 7,5" Paper Faced PolyISO between Rafters (Cathedral Ceiling, roof is 9/12 Pitch)
  • Appliances:
  • Water Pump: Grundfos SQ-5, Soft Start 120V Deep Well pump, 260' deep pushing to 50 Gal Pressure tank then 75' to Cabin. Max Wattage 1000W @ 45PSI. REF: https://us.grundfos.com/products/find-product/sq.html
  • Unique Offgrid Classic propane cook stove: REF: https://uniqueappliances.com/
  • Danby (Magic Chef same) Apartment Size Energy Star Fridge (uses 220kwh per yr)
  • EccoTemp FVI12-LP On-Demand Water Heater for Hot Water. (not suggested, get a 45 series or better brand !)
  • Takagi TH-3-m Condensing On-Demand Heater (used for Radiant Heating exclusively as I had Antifreeze in my system) (got from Radiant Supplier best deal out there)
    **NB** I run a separate Hot Water System from my Radiant System. The other option is to use one On-Demand unit for both, very possible and not hard, The Radiant Company can design it either way for you, no extra charge, it's a part of their service and I can only PRAISE Them for their amazing work, quality products & support, and I do "not" praise anyone lightly !
The efficiency is a win with the slab & hyper insulation. Winter -30C, inside 25C, Radiant only run 2 hrs within a 24 hour period to maintain 25C (floor sensor). Summer: 35C outside, 21C inside, NO AC or Fans just open windows. Slab itself never goes above 20C in summer, it regulates everything inside. Should Note, I am on the South Face of a Granite Ridge, 1200 foot fall in front of me, this property get's the heat & in a bad heatwave 40C is not a shocker. The Cabin itself is shaded by Scotch Pines & Cedars on the south & west sides and nestled into a forest nook. Solar System is mounted to the side of a 20' Sea Can 50' from Power House.

ENERGY SYSTEM Location:
I appreciate you are presently using an RV while Prepping & Building and that results in a few compromises. I would very strongly urge you to consider building a separate "PowerHouse" to contain your solar equipment, batteries etc. Inverters can be quite noisy and there are obvious safety/security issues. I'm fairly North (up around Algonquin Park, Ontario Canada) and have my PowerHouse & PumpHouse as a combined building which has my solar system, water well-head & 50 Gallon pressure tank. Due to my location, I installed a recovered RV Heater (Suburban NT-20S) which I cooped out of a nearly new wrecked RV that keeps the building at 10C/50F in winter... (This building is similar to the cabin, with regards to FPSF & Insulation in walls & roof). Water & Powerlines run to house via 4" Underground Conduit Pipes. Powerhouse will enable you to setup a Genset Doghouse next to it (if wanted) and keep things isolated & safe and not next to your bedroom window as it were.

Hope it helps somewhat, Good Luck.
 

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Porch

Solar Addict
Joined
Jan 17, 2021
Messages
267
@Steve_S Has some excellent advice. Hyper insulation is the key here. Most home builders go with the cheapest and easiest construction method they know and rely on HVAC to make up the slack.
 

off grid newby

New Member
Joined
Oct 6, 2021
Messages
4
Thanks for the replies and good feedback.

As I will only have one or two 220 loads, the Growatt option would require a transformer to reduce the majority of my demand adding just another piece to the puzzle. I will go with the MPP option, utilizing one now with the RV and adding the second in parallel later when cabin is completed.

I believe I want to go with the 440 watt mono panels, and mount on a movable ground sled so I can drag it over closer to the building when complete and adjust through the year for optimum coverage. Always thought I would position on the final roof, but prevailing roof will face E/SE and will lose afternoon sun even if I place panels on the back roof. I can always modify later, so I think better to start on the ground first. Building direction is dictated by screened porch side facing the lake I built last year.

The "cabin" could actually be called a "barndominium" as it will be a metal roofed pole barn, but cabin is shorter. The center 30/50' will be finished out, with a 12/50' screened porch on one side and a 12/50' storage area on other side. The storage side is where the inverters and batteries will live, as well as water tanks, filters, pumps and heaters. This will keep them protected and somewhat climate controlled, but separate from living area. Minimum windows with tint, extra insulation where it counts and reflective roof color are all part of the plan. We don't have extreme winters only occasionally dipping below freezing, but an adequate but efficient AC is a must.

Power company estimate was about 30K to run power into my property, so anything less than that is doable knowing that there will also be no recurring monthly power bills to follow. With the couple inverters, initial panels and hardware I should be around 6K. Now comes the most expensive part with the batteries. I am not ready to build 48 volt battery packs yet, so will be crunching numbers on best available ready builds. I will start out with a couple, and expand as needed as my project completes and I cut the RV loose.

Thanks again for the feedback.
 

Porch

Solar Addict
Joined
Jan 17, 2021
Messages
267
Your 220v loads will grow. I started off with no 220v loads, but I have more options with 220v AC units. Welder and plasma is 220v. I put a VFD to convert it to 3 phase for slow ramp up on the well and air compressor.

I went with the same metal building idea, but built inner walls about a foot away from the outer walls. All with steel studs. Then filled the gap with fiberglass insulation I got for free out of a demolished store along with new insulation. Best thing I did in the entire build for my desert living. 110F outside, and the split unit ACs keep the place nice and cool in the summer, and warm in the winter and barely run at all.
 

off grid newby

New Member
Joined
Oct 6, 2021
Messages
4
You are probably right about loads growing, but from the beginning I purchased a generator capable of running welders and air compressors for those random times that I use them. First build on site was covered storage utilizing two 20' containers and steel trusses to house the tractor, atv, utv and equipment, and that will remain as is as a stand alone equipment area. If I find I need more 240v supply beyond the cabin AC units, I should have plenty of room to expand the system. Containers and RV currently are only using Harbor Freight panels and 12v deep cycle batteries. I purchased a smaller remote start inverter generator once we brought in the RV, but only use it when running AC.

I set up a rainwater collection system with tank and simple Northern Tool 12v on demand pump that works great for washing down equipment and now also supplying water for RV. On this location putting down a well would be a 70/30 chance that you would tap into heavy iron and/or sulfur water, so I will go with the rainfall system for the cabin also. Instead of one 500 gal. tote will install two totes tied together for 1000 gal supply. I wont need the 220v supply for a deep well pump if I go this route. Keeping the tanks enclosed under roof and dark will make treating and filtering easier than the one I have outside the containers. Even with that one only a few ounces of clorox once a month keeps it clear and usable. For the cabin will install additional filtration system as well.

I will add a few pics of my progress so far.

Thanks again for any or all feed back as I learn more about solar power.
 

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off grid newby

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Oct 6, 2021
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Hasn't been an issue with the tank I set up at the equipment shed over a year ago. I only have one gutter collecting from the pitch farthest from the trees, and capped it off with a micro screen filling any gaps with silicone. The IBC totes have a lowest point drain, so if any material were to collect it should draw toward the pump. There is a inline screen filter before the pump, and I have been using an additional inline RV water filter since I started using this tank for that supply. Sediment and debris have not been an issue as I have not had any screen or filter plugging issues. Initially wasn't treating the tank, but noticed after time in the sun that there was some green spots forming around the upper water line. Started adding a shot of concentrated bleach every few weeks, and crystal clear again. Was adding a little too much at first and could smell bleach in the water, but weened back to only a few ounces if I see the color starting turn. The system I intend to set up in the cabin will be similar but double capacity, along with additional cartridge type filter system. I also earlier stated that I bought the pump from Northern Tool, but found the box and remembered buying this pump online. SeaFlo 51 Series, Automatic Demand Diaphragm Pump,12v, 5.5 GPM @ 60 PSI. This pump has worked flawlessly, and the pressure and flow are more than adequate.

To clarify, we do not use this water for drinking, but is fine for bathing, dishes or anything else. If we were to put down a well in this area with the iron and sulfur content, we would not drink it either so no real trade off.
 

Kornbread

Solar Enthusiast
Joined
Sep 16, 2021
Messages
56
I would imagine, if you kept an eye on the bleach level, there would be no issue using this for drinking water. If/when you decide to move out there, as in a more permanent residence, a test kit may be in order. IIRC, they are $ very reasonable. You are keeping the tanks indoors, but I wonder if painting them might further help alleviate the algae?
 

Rednecktek

Solar Addict
Joined
Sep 8, 2021
Messages
427
Y
and mount on a movable ground sled so I can drag it over closer to the building when complete and adjust through the year for optimum coverage.
You might want to grab a calculator and add up the weights of the panels, lumber, channel steel, etc and see if you'll need a tractor to move all that weight around. Just thinking ahead. :)
 
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